Cellular sensitivity to low dose ionizing radiation

Cellular sensitivity to ionizing radiation is largely understood in terms of their DNA damage repair capacity. Efficient repair of DNA damage leaves irradiated cells unharmed. The observed differential responses of high doses (>500 mGy) and low doses (<200 mGy) of ionizing radiation are generally accounted by the differences in DNA damage repair processes. High dose radiation-induced cellular toxicity is gainfully employed in cancer radiotherapy. However, effects of low dose radiation (LDR) on cells and organisms have remained controversial. Some studies have reported LDR suppressive effects to high dose radiation-induced cancer. The purpose of this article is to briefly discuss the current understanding of low dose-induced DNA damage in cell survival responses. Evidence is accumulating to suggest that low dose irradiated cells remain insensitive to a window of LDR. Clearly, these findings give support to negate the linear dose effect assumptions followed in radioprotection regulation and also address the question of safety issues in utilizing LDR therapies to treat cancer and noncancer diseases. A range of new LDR technologies seem to be in waiting for improving human health. (author)